Use variables in a SELECT INTO FROM command

Question

Hi,
How do I use variables within a select into from command? I want to loop through SYS.DBA_TABLES using a cursor and count the number of rows in a
selection of tables an then insert into a cardinality table.
The count of rows will be stored in a variable called CNT, that bit is easy however I need a variable in the FROM clause because that
value changes with every iteration of the cursor.
e.g.
CNT := 0;
TN := "MyTable";
select count(*) into CNT FROM TN;
insert into cardinality (table_name, row_count) values (TN, CNT);
This is Oracle 9i and I need the row counts in a separate table as they are shipped over to a different environment for analysis purposes.
Any ideas?
Regards
Dave
Edited by: Yorky001 on Sep 15, 2010 10:32 AM

Answer 1

Hi,
Thanks for the info, unfortunately I can get neither example to work on this 9i system, could well be pilot error as I only ever get
to do any Oracle about once per year. In the first query I have tried both "user_tables" and SYS.DBA_TABLES, same result.
set serveroutput on size 1000000;
DECLARE
row_count INTEGER;
vstr VARCHAR2(500);
vstr1 VARCHAR2(500);
BEGIN
vstr := 'SELECT count(*) FROM ';
dbms_output.put_line(vstr);
FOR i IN (SELECT table_name FROM user_tables WHERE rownum < 10) LOOP
vstr1 := vstr || i.table_name;
EXECUTE IMMEDIATE vstr1
INTO row_count;
dbms_output.put_line(i.table_name || ':' || row_count);
END LOOP;
END;
This one complains about the execute immediate line.
Error report:
ORA-00933: SQL command not properly ended
ORA-06512: at line 12
00933. 00000 - "SQL command not properly ended"
*Cause:   
*Action:
BEGIN
FOR i IN (select
table_name,
to_number(
extractvalue(
xmltype(
dbms_xmlgen.getxml('select count(*) c from '||table_name))
,'/ROWSET/ROW/C')) count
from user_tables
where rownum<6) LOOP
dbms_output.put_line(i.table_name || ':' || i.count);
END LOOP;
END;
ORA-19206: Invalid value for query or REF CURSOR parameter
ORA-06512: at "SYS.DBMS_XMLGEN", line 121
ORA-06512: at line 1
ORA-06512: at line 2
19206. 00000 - "Invalid value for query or REF CURSOR parameter"
*Cause:    The queryString argument passed to DBMS_XMLGEN.newContext was not a valid query, or REF CURSOR.
*Action:   Rewrite the query so that the queryString argument is a valid query or REF CURSOR.